Fig. 148.—Pes Calcaneo-valgus with excessive arching of foot.
Fig. 149.—Pes Calcaneo-valgus, the result of Poliomyelitis.
Pes Calcaneo-varus.—In this rare deformity the heel is depressed and the sole of the foot looks inwards.
Pes Cavus.—In this deformity, which is known also as hollow claw-foot, pes arcuatus, or pes excavatus, the longitudinal arch of the foot is exaggerated as a result of the approximation of the balls of the toes to the heel ([Fig. 150]). It is most frequently met with as an addition to pes equinus or pes calcaneus of paralytic origin, and has already been described. There is a mild form which is congenital, and which is quite independent of paralysis; another variety occurs in diseases of the spinal cord, such as Friedreich's ataxia.
The name hollow claw-foot appropriately indicates the clinical appearances. The arch is exaggerated and the instep abnormally high; there is hyper-extension of the toes at the metatarso-phalangeal joints, and plantar-flexion at the inter-phalangeal joints; the plantar fascia and muscles are shortened. The footprint shows that neither border of the foot touches the ground. The patient complains of pain in the instep, of painful corns over the heads of the metatarsal bones, and of difficulty in getting properly fitting boots.
Treatment should first be directed towards the equinus or calcaneus element of the deformity, for if these are corrected the cavus condition tends to disappear. Exercises and massage should be persevered with, and boots without heels should be worn. The contracted structures in the sole may require to be divided, either subcutaneously or by the open method, as a preliminary to forcible correction, and the hallucis tendon may be brought through the head of the first metatarsal. In aggravated cases the talus and the heads of the metatarsal bones may be excised.